The field of art to which the claimed invention pertains is hydrocarbon separation. More specifically, the invention relates to a process for separating a para-isomer from a feed mixture comprising at least two bi-alkyl substituted monocyclic aromatic isomers, including the para-isomer, the isomers having from 8 to about 18 carbon atoms per molecule which process employs a particular zeolitic adsorbent and a particular flow scheme to selectively reject and subsequently recover the para-isomer from the feed.